From 3bb497c61d743ba811e7f501e54cc5071216e1f5 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Tue, 28 Aug 2018 21:44:16 +0200 Subject: xtables: Fix for deleting rules with comment Comment match allocation in command_match() and nft_rule_to_iptables_command_state() were misaligned in that the latter set match_size to just what is required instead of what the match needs at maximum like the further. This led to failure when comparing them later and therefore a rule with a comment could not be deleted. For comments of a specific length, the udata buffer is padded by libnftnl so nftnl_rule_get_data() returns a length value which is larger than the string (including NULL-byte). The trailing data is supposed to be ignored, but compare_matches() can't not know about that detail and therefore returns a false-negative if trailing data contains junk. To overcome this, use strncpy() when populating match data in nft_rule_to_iptables_command_state(). While being at it, make sure comment match allocation in that function is identical to what command_match() does with regards to data allocation size. Also use xtables_calloc() which does the required error checking. Signed-off-by: Phil Sutter Signed-off-by: Florian Westphal --- iptables/nft-shared.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) (limited to 'iptables/nft-shared.c') diff --git a/iptables/nft-shared.c b/iptables/nft-shared.c index 4557f17d..c8414294 100644 --- a/iptables/nft-shared.c +++ b/iptables/nft-shared.c @@ -646,7 +646,7 @@ void nft_rule_to_iptables_command_state(const struct nftnl_rule *r, if (nftnl_rule_is_set(r, NFTNL_RULE_USERDATA)) { const void *data; - uint32_t len; + uint32_t len, size; struct xtables_match *match; struct xt_entry_match *m; @@ -656,15 +656,12 @@ void nft_rule_to_iptables_command_state(const struct nftnl_rule *r, if (match == NULL) return; - m = calloc(1, sizeof(struct xt_entry_match) + - sizeof(struct xt_comment_info)); - if (m == NULL) { - fprintf(stderr, "OOM"); - exit(EXIT_FAILURE); - } + size = XT_ALIGN(sizeof(struct xt_entry_match)) + match->size; + m = xtables_calloc(1, size); - memcpy(&m->data, get_comment(data, len), len); - m->u.match_size = len + XT_ALIGN(sizeof(struct xt_entry_match)); + strncpy((char *)m->data, get_comment(data, len), + match->size - 1); + m->u.match_size = size; m->u.user.revision = 0; strcpy(m->u.user.name, match->name); -- cgit v1.2.3